Safety systems for electric fuel pumps



June 20, 1961 w. F. scHULTz 2,989,644

SAFETY SYSTEMS FOR ELECTRIC FUEL PUMPS Filed Jan. 25, 1960 FUEL PUMP TTOE/VEV United States Patent C)` 2,989,644 SAFETY SYSTEMS FOR ELECTRIC FUEL PUMPS Werner F. Schultz, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Jan. 25, 1960, Ser. No. 4,440 6 Claims. (Cl. 290-36) This invention relates to systems for electrically driven fuel pumps and more particularly to electric fuel pump systems having a safety aspect and suitable for use in automotive vehicles.

An electrically operated fuel pump serving the engine of a vehicle will continue to operate despite an accident or stoppage of the engine with the ignition turned on unless some provision be made to avoid such operation. Obviously, a shut-olf device should be provided which is automatically operative, when the occasion arises, to prevent a continuing ow of fuel which would be conducive to re or cause other difficulties.

An object of the present invention is to provide an improved fuel pump electrical system which is simple and inexpensive and possesses the required safety stop features.

A feature of the present invention is an electrical system including a single pole, single throw relay for conducting a pump power supply from a generator circuit during normal running of an engine and from a starter circuit during the engine cranking cycle with opening of the relay contacts being automatic to satisfy safety requirements.

These and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawing is presented a diagrammatic representation of an electrical fuel pump system for an automotive vehicle as one embodiment of the present invention. A fuel pump with an electric motor 10 is adapted to supply fuel to an internal combustion engine and is driven by power derived from a battery 12 during engine starting as will further appear. The pump motor is grounded at 14 and the battery is grounded at 16. An engine ignition line 18 is controlled by an ignition switch 20 and is connected to the battery to serve as a voltage supply. A line 22 connects the battery side of the switch 20 with the lield coil connection of an engine starter series wound type motor 24 and is controlled by a starter switch 26. 'Ilhe starter motor commutator is grounded at 28. The eld coil of the starter motor 24 is also connected by a line 30 to one end of a coil 31 in a single pole, single throw relay generally indicated at 32. A line 34 is controlled by a generator cutout 36 and connects the battery 12 or voltage supply line 18 with the commutator of a generator 37. The load circuit of the latter is grounded at 39. Line 34 is also connected to the other end of the relay coil 31. The relay 32 is normally open but when its contacts 35 and 38 are closed, a circuit is established through a line 40 leading from the line 18 to the pump motor 10.

The generator cut-out 36 is a conventional magnetically operated switch. Its function is to connect the generator 37 to the battery 12 when the generator is operating at speeds suiciently high to charge the battery. At low generator speeds such as during engine cranking, the cutout 36 contacts are open preventing the battery from discharging back through the generator.

To start the engine, the ignition switch 20 must first be closed. Subsequent closure of the starter switch 26 not only cranks the engine but energizes the relay coil 31 to close the normally open relay 32. At this time the starter lield coil connection is at battery voltage, the relay circuit is grounded at 39 through the generator armature connection and the cutout 36 is open. The pump 10 there Patented June 20, 1961 "ice ' fore operates at battery voltage during engine cranking when the generator 37 is inetfective for its normal operation.

When the engine begins to run normally there is a reversal of current in the relay circuit, the latter being grounded at 28 through the starter but the period of reversal is so brief that the pump does not cease operation before the generator voltage is sutiicient to hold the relay contacts 35 and 38 closed. The pump motor 10 therefore continues to run but on generator voltage with the cutout 36 closed.

If the engine s stopped by opening of the ignition switch 20 as is normally the case or if the engine stops because of an accident, a burned out generator or for some other reason and there is a lack of voltage in line 18 or line 34 the relay 32 will automatically assume its normal open condition and the pump' motor 10 will be stopped.

Obviously, the automatic stoppage or the inoperativeness of the pump motor 10 may be overcome by manual operation of the relay 32 if the need arises.

It is to be noted that the pump control circuit from the Voltage supply includes no switching in itself and only a simple relay 32 is employed in the pump power supplysimplicity is a special characteristic of the system, no need arising for special parts or switches and any voltage drop across the starter does not affect the pump operation.

In place of the generator cutout 36 a stack of selenium rectiers or a semiconductor diode could be used, the specic device employed not being material insofar as the present invention is concerned.

I claim:

1. An electrical system for a fuel pump, said system including a voltage supply, a starter motor, a starter switch, a generator, an electric pump motor, and a normally open single pole, single throw relay with an actuating coil, one end of said coil being connected to said starter motor and through said starter switch to said voltage supply, the other end of said coil being connected to said generator and to said voltage supply, and said relay being arranged to connect said pump motor to said voltage supply when said coil is energized.

2. An electrical system including a voltage supply, an engine starting motor, an engine driven generator, an electric fuel pump motor, a normally open single pole, single throw relay with an actuating coil, a starter switch for connecting said starter motor in parallel with said coil and generator to said voltage supply, a line leading from said voltage supply to said pump motor and controlled by said relay, and Ithe arrangement being such that energizing of said coil closes said relay.

3. An electrical system as set fort-h in claim 2, said voltage supply including a battery and an ignition line controlled by an ignition switch.

4. An electrical system as set forth in claim 2, said voltage supply including a battery and an ignition line controlled by an ignition switch, said starter switch and generator being connected to the battery side of said ignition switch, and said relay being connected `to the other side of said ignition switch.

5. An electrical system including a voltage supply, an engine starting motor, an engine driven generator with a cutout switch, an electric vfuel pump motor, a normally open single pole, single throw relay with an actuating coil, a starter switch for connecting said starter motor in parallel with said coil and generator to said voltage supply, said voltage supply being connected to said pump motor through the contacts of said relay, and the arrangement being such that deenergizing of said coil by a drop in speed of said generator opens said relay to stop said pump motor.

6. An electrical system including a voltage supply, an engine starting motor, an engine driven generator with a cutout device, an electric fuel pump motor, a normally open single pole, single throw relay with an actuating coil, a starter switch in parallel with said cutout device for connecting said starter motor in parallel With said coil and generator to said voltage supply, said voltage supply being connected to said pump motor through the contacts of l said relay, and the arrangement being such that deenergzing of said coil by a drop in speed of said generator opens said cutout device and said relay to stop said pump motor.

No references cited. 

